Final answer:
The weight of living organisms in an ecosystem at a particular point in time is called biomass, representing the total organic matter within an ecosystem at a particular trophic level.
Step-by-step explanation:
The weight of living organisms in an ecosystem at a particular point in time is called biomass. Biomass refers to the total weight, at the time of measurement, of living or previously living organisms within a unit area of an ecosystem at a particular trophic level. This includes not only the plants and animals that are visible but also the microorganisms within the soil. It is a measure of the amount of organic matter present in the individual organisms or in all the organisms at a given trophic level. Annual biomass production is influenced significantly by abiotic components like climate, with warm and wet conditions leading to higher levels of productivity and biomass. In this way, biomass interacts with both the biotic and abiotic elements of its environment, contributing to the overall functioning of the ecosystem.